Can you guys please explain something? Will that command automatically max out your processor to 100%? If it does, what will you learn? It's not like running real world applications. Wouldn't a test like bsnoel recommended (no offence ClunkCluck) be better? I'm still relatively new to this Mac thing, so please be gentle.

No, it's not like running real world applications. It's more of a simple way to do a synthetic test. Provided it does what it should (maxing out each processor core), it's a decent way to induce a "worst case scenario" for the processor. If your cooling setup can survive that, then it probably can survive anything a "real world" application can produce.

It's useful because it's easy, and seems to push each core to its maximum, however as bsnoel pointed out, it may not be stressing the FPU portions of the processor, so it may not be as perfect as I'd like. It's also not challenging any other components, like memory, busses, and the hard drive, so heat levels may not be as high as they could possibly get to.

I would surmise the test that bsnoel recommended would be more useful, but mine's a bit easier to run. Each has its place, I suppose.

That's what I was thinking, but thanks for explaining it out. Wow, I just learned a lot reading the last 6-8 posts. I would still like to do this and a hard drive upgrade down the road when the prices come down on 160GB hard drives and Core 2 Duos. I have like every Mac mini processor upgrade article bookmarked.

Can you guys please explain something? Will that command automatically max out your processor to 100%? If it does, what will you learn? It's not like running real world applications. Wouldn't a test like bsnoel recommended (no offence ClunkCluck) be better? I'm still relatively new to this Mac thing, so please be gentle.

Modern CPUs have many units that perform different functions. ALU, AGU, FPU, SSE unit, schedulers, etc. These work together to perform different tasks.

The yes command is used to answer yes to prompts or to loop another response. Using "yes no" would loop no until you stop it. Alternately, typing "yes" alone would loop "y". So, the yes > /dev/null command puts the system into a loop of repeating "y"s as fast as the processor can type them. This will load the CPU, but I don't think it loads every portion of the CPU it probably loads the ALU mostly.

The Xgrid code uses advanced mathematics to run very large complex calculations. This stresses more portions of the CPU at once, because Xgrid is doing more work than looping (y)s. I doubt either method truly fully loads the processor, but my method might stress more portions simultaneously. For example neither probably stresses the SSE units.

Without a doubt either method would get the CPU cooking hot in short order. My method would probably keep more transistors in play and might make the CPU get hotter. Either way, if you hit 100C on the Core 2 Duo, its going to shutdown.

However, I have an ulterior motive in play. I'm trying to get more 123macmini users interested in participating in the Stanford Xgrid. The Stanford Xgrid benefits humanity, by working to find new treatments for heart disease, asthma, etc. It also helps the Mac community, by displaying an impressive showing of Mac horsepower at work for the common good._________________Mac Pro Quad 2.66GHz, PowerMac G5 2.3 GHz, iMac Core Duo 17", MacBook Pro 2GHz, MacBook Pro 2.2GHz, Mac mini Core 2 Duo 1.83GHz. Multi-K9 Security System. No false alarms, just lots of sharp teeth.
www.grweather.com

The Xgrid code uses advanced mathematics to run very large complex calculations. This stresses more portions of the CPU at once, because Xgrid is doing more work than looping (y)s. I doubt either method truly fully loads the processor, but my method might stress more portions simultaneously. For example neither probably stresses the SSE units.

By the looks of your signature, it looks like you have quite a few other Intel Macs. How do they fair with Xgrid in comparison to your Core 2 Duo Mac mini?

The Xgrid code uses advanced mathematics to run very large complex calculations. This stresses more portions of the CPU at once, because Xgrid is doing more work than looping (y)s. I doubt either method truly fully loads the processor, but my method might stress more portions simultaneously. For example neither probably stresses the SSE units.

By the looks of your signature, it looks like you have quite a few other Intel Macs. How do they fair with Xgrid in comparison to your Core 2 Duo Mac mini?

Bsnoel. What temp is your 160GB Seagate running at? I installed that 160GB WD and it's running between 55C-58C. That seems a little high to me.

Keep in mind, that I modified my fan speed slopes and my fans kick in sooner and harder than a stock mini. I ran a "erase free space" job on the disk and the disk was running between 122 - 129F. Mostly around 122f, but near the end of the job after writing 100+GB I had slowly crept up to 129. Under normal operation, I'm running around 116F._________________Mac Pro Quad 2.66GHz, PowerMac G5 2.3 GHz, iMac Core Duo 17", MacBook Pro 2GHz, MacBook Pro 2.2GHz, Mac mini Core 2 Duo 1.83GHz. Multi-K9 Security System. No false alarms, just lots of sharp teeth.
www.grweather.com

Keep in mind, that I modified my fan speed slopes and my fans kick in sooner and harder than a stock mini. I ran a "erase free space" job on the disk and the disk was running between 122 - 129F. Mostly around 122f, but near the end of the job after writing 100+GB I had slowly crept up to 129. Under normal operation, I'm running around 116F.

Thanks for getting back with me. It seems to be running between 49C-52C most of the time now, so it looks like we are about in the same ballpark. I feel a little better now.

If you replace the CPU and hard drive do you just have to just reinstall OSX from the DVD's, or do you also have to update the firmware? I thought I read something about having to update firmware somewhere. I'll be replacing everything in 2 Mini's in the next couple of weeks (CPU, drive, DVD, memory, motherboard, case...hey wait a minute! Somebody stop me!! )

If you replace the CPU and hard drive do you just have to just reinstall OSX from the DVD's, or do you also have to update the firmware? I thought I read something about having to update firmware somewhere. I'll be replacing everything in 2 Mini's in the next couple of weeks (CPU, drive, DVD, memory, motherboard, case...hey wait a minute! Somebody stop me!! )

Bob

You don't have to, but it's probably a good idea to keep on top of the firmware updates. You'll definitely need to reinstall OS X from the two restore disks when you swap out the drives. The rest of the components are basically plug and play.